常规PLC和安全PLC的区别

本文介绍了常规PLC与安全PLC的很多不同点，然后通过安全PLC的CPU、I／O模块举例说明了它们不同的具体内容。     

TRICON系统在二化PLC改造中的应用

TRICON系统是一种具有高容错能力的可编程逻辑及过程控制系统,广泛应用于石油化工装置的安全仪表系统,火灾及气体检测保护系统FGS,应用于铁路运输行业的康吉森MCIS铁路微机联锁系统及大型透平压缩机组综合控制系统,在化肥厂一二化都有应用,效果都比较让人满意。因此,针对二化PLC系统老化,无法满足安全生产的需要,采用TRICON系统进行更新换代,以保证装置的安稳长满优地运行。     

怎样选择安全PLC

表述了选择安全PLC的系统方法论.它将描述基于技术要求(如安全要求)和商业要求(如可用性和生命周期成本分析)对安全PLC的评价.     

催化主风机TS3000控制系统功能完善

一 存在问题 中石化洛阳分公司一催化3#主风机控制系统在2001年5月进行了整体升级改造，采用Triconex公司的TS3000三重冗余容错PLC控制系统，系统投用以来总体运行状况良好，但也存在两大问题：     

基于双CPU的冗余控制研究与实现

根据工业控制系统中对PLC的高可靠性要求,提出了双CPU的PLC冗余控制措施,并详细分析了基于A-B ControlLogix PLC的双CPU冗余控制的具体实现方法,包括软件冗余实现方式和硬件冗余实现方式。     

基于AB Control Logix的水库闸门冗余监控系统

针对现代水库闸门的自动化需求,设计了基于Allen—Bradly公司Control Logix的水库闸门冗余监控系统。利用以太网和控制网构建了系统的硬件组网方案。在分析Allen～Bradly公司PLC软件编程环境特点的基础上,设计了PLC控制程序,并使用RSView组态软件编制了上位机和触摸屏的控制界面。为保证系统连续安全运行,采用硬件冗余的方式实现冗余控制。实践证明该系统达到了操作方便、性能稳定的控制效果。     

西门子冗余PLC系统在高炉中的应用

本文以具体实例讲解了西门子冗余PLC系统在高炉中的应用，讲述了西门子冗余PLC的系统构成、特性、软硬件组态、故障处理等，同时详细叙述了高炉的数据通讯和故障处理过程。     

三重冗余容错控制系统在压缩机防喘振中的应用

扬子石化炼油厂新建160万吨延迟焦化气体脱硫装置富气压缩机，采用的是沈阳鼓风机厂制造的2MCL527型两段离心式压缩机和杭州汽轮机厂制造的NG32／35背压式汽轮机，在机组所有的控制中，防喘振控制是最重要和最复杂的控制之一。控制系统选用Triconex公司TS3000三重冗余容错控制系统，TS3000的防喘振控制基于三重模件冗余容错结构的控制器，采用三取二表决提供高度完善、广泛诊断、不间断的过程操作，该系统不仅可实施对机组的防喘振控制，还可实施机组的安全保护控制。在实施过程中，采用了该系统进行压缩机防喘振控制和机组安全保护控制相结合的方案，有效提高了机组运行效率和安全保护速率。实践证明这是一套成功的方案。     

采用小型PLC搭建冗余控制系统的研究与实践

介绍了采用小型PLC实现冗余控制方案中的硬件配置,对冗余控制系统的关键点——主从PLC的判断及切换原理进行了阐述,分析了实现冗余控制所需占用的IO点以及采用小型PLC搭建的冗余控制系统中输入输出信号的处理方法,并以OMRON PLC为例阐述了程序的实现方法,为IO点数少但需要实现冗余控制的场合提供了一种低成本的解决方案。     

起爆药连续化合自动控制系统研究

针对起爆药生产中存在的安全与质量一致性问题,设计了基于S7-300 PLC的起爆药连续化合自动控制系统,同时结合工控组态软件WinCC开发了上位机监控系统,建立了上位机与PLC之间的MPI数据通讯,完成了过程监控。冗余设计是整个系统的关键点。实际运行表明该系统安全可靠,提高了起爆药生产的自动化水平。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.